The present invention relates generally to pharmaceutical compositions containing peptides having immunomodulating properties and more particularly to pharmaceutical compositions of tryptophan-containing dipeptides and methods of use thereof.
The lymphoid system performs critical functions in animals and man that include preventing and combating infection, and surveillance and immune elimination of tumor cells. Loss of immune function leads to an immunocompromised status that can predispose the host to serious and life-threatening disease. Functional abnormalities may be present in any of the elements that participate is mediating an immune response, e.g., cellular or humoral elements such as granulocytes, lymphocytes, complement, antibody, or cytokines.
Immune deficiency may result from many different etiologies including hereditary genetic abnormalities (e.g., Chediak-Higashi Syndrome, Severe Combined Immunodeficiency, Chronic Granulomatous Disease, DiGeorge Syndrome) exposure to radiation, chemotherapy, heavy metals or insecticides; or, acquired as a result of bacterial, viral, parasitic or fungal infection.
The immune system is normally regulated by cellular and soluble elements and loss of regulatory control may result in autoimmune disease, e.g. multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, Sjogren""s syndrome, and insulin-dependent type I diabetes. Conventional immunosuppressive drugs that are used to treat autoimmune diseases have generalized and non-specific effects on the immune system that can predispose infection and increase the risk of malignancy. Methods to compensate for decreased innate resistance to infection following radiation- or chemotherapy (or radiation therapy) are of great therapeutic value.
Thymus tissue extracts affecting proliferation and/or differentiation of T-lymphocytes have been reported, including e.g., xe2x80x9cthymosinexe2x80x9d (1), xe2x80x9cthymalinexe2x80x9d (2), xe2x80x9cT-activinexe2x80x9d (3), xe2x80x9cthymosin-xcex11 (4), xe2x80x9cthymosin fraction 5xe2x80x9d (a heat-stable fraction isolated from calf thymus extracts), and others. Commonly tissue extracts exist as complex mixtures that includes polypeptides, e.g., several peptides have been isolated from Thymosin fraction 5, such as Thymosin alpha1 (28 amino acids, U.S. Pat. No. 4,079,127), Thymosin beta4 (44 amino acids, Low et al., PNAS, 78,1162-1166 (1981)), Thymosin beta8 (39 amino acids, U.S. Pat. No. 4,389,343) and Thymosin beta9 (41 amino acids, U.S. Pat. No. 4,389,343). Thymosin-xcex11 fragments and dimers have also been described in U.S. Pat. Nos. 4,396,605; 4,470,926; 4,612,365; and 4,910,296.
Widespread use of purified tissue extract fractions in medical practice has been hindered by variability of preparations, low yields, lack of highly purified and characterized reproducible sources, and problems associated with preparing complex mixtures having standardized biological potency. In addition, complexity and variability of tissue extracts potentially effects stability, toxicity, and safety. Alternatively, synthesis of large biologically active polypeptides is at present difficult and expensive particularly under manufacturing conditions required for pharamaceutical preparations.
T-lymphocytes participate in cellular and humoral immune responses triggered by binding of foreign molecules to lymphocyte cell surface receptors. The erythrocyte rosette receptor defined by the CD2 cell functions as both an intercellular adhesion molecule and a cell surface signal transduction molecule. CD2 reportedly binds PHA and is involved in PHA-mediated lymphocyte blastogenesis. Binding of anti-CD2 antibodies to the CD2 receptor is also reportedly able to trigger T-lymphocyte blastogenesis and this pathway of activation may be independent of the CD3/T-cell receptor complex. T-cell CD2 binding to LFA-3/CD58 may mediate intercellular adhesive binding of T-lymphocytes to B-lymphocytes and thymic epithelial cells. CD2 binding to CD59 and CD48 ligands may facilitate intercellular binding to other cell types. Lymphocyte cell surface CD4 and CD8 molecules define MHC class specificity of T-helper, T-suppressor and cytotoxic T-lymphocytes. (Paul, W. E. Ed. 1993. xe2x80x9cFundamental Immunology, 3rd. Editionxe2x80x9d, Raven Press, N.Y. pp.541-5.)
Methods have been discovered for treating immunocompromised subjects to increase one or more indicia of cell mediated immunity (CMI), humoral immunity, or innate resistance to infection, by administering pharmaceutical preparations of Rxe2x80x2-Glu-Trp-Rxe2x80x3. The results of in vitro studies showed that L-Glu-L-Trp dipeptide increased expression of accessory molecules on the surface of thymocytes and mature T-lymphocytes as evidenced by i) increased E-rosette forming cells (E-RFC) in thymocyte cultures after incubation with dipeptide; ii) increased E-RFC in cultures of thymocytes from aged animals after incubation with dipeptide; and, iii) increased expression of OKT 4+ in cultures of human peripheral blood T-lymphocytes from patients with secondary immunodeficiency syndromes following incubation with dipeptide. L-Glu-L-Trp dipeptide did not measurably upregulated CD8 expression on lymphocytes. Increased expression of CD2 and CD4 accessory molecules on T-lymphocytes is compatible with a heighten the state of innate or induced immunity to infection, e.g., by upregulating T-helper and cytotoxic T-lymphocytes to respond to lower levels of antigen. To test this hypothesis in vivo studies were conducted in which the immunological effects of L-Glu-L-Trp dipeptide were tested in experimental animal models. L-Glu-L-Trp treatments mobilized and altered tissue distribution of lymphocytes in experimental animals, activated monocytes and increased phagocytic activity of granulocytes. Animal model studies in mice showed that treatments with L-Glu-L-Trp decreased incidence of mortality from acute bacterial infection with E. coli, Pseudomonas aeruginosa, and staphylococci. In irradiated guinea pigs and 5-fluorouracil (5-FU) immunosuppressed mice L-Glu-L-Trp treatments increased the number of lymphocytes and T-lymphocytes in peripheral blood. When injected locally, L-Glu-L-Trp increased the activation state of resident tissue macrophages (as measured by NBT reduction); and, promoted neutrophil infiltration into the tissue in response to a sterile inflammatory mediator (proteose peptone). L-Glu-L-Trp treatments increased in vitro expression of CD4 (but not CD8) on lymphocytes isolated from patients with secondary immunodeficiency syndromes. Clinical studies showed increased indicia of CMI, humoral immunity or innate immunity in the following patients treated with L-Glu-L-Trp pharmaceutical preparations: namely, patients with acute and chronic infections including respiratory infections, pleuritis, pelvic inflammatory diseases, infections of leprosy, tuberculosis, staphylococcal pyoderma, dengue fever, chronic viral hepatitis, Shigella dysentery, malaria, influenza, and tuberculosis. L-Glu-L-Trp treatments also i) alleviated certain clinical symptoms in patients with autoimmune disease and allergy; ii) decreased complication rates and increased lymphocyte counts in cancer patients following radiation therapy; iii) increased lymphocyte counts in individuals exposed to accidental environmental radiation and surgical thymectomy; and, iii) increased lymphocyte counts in patients with secondary immunodeficiency. L-Glu-L-Trp showed efficacy in both prophylactic and therapeutic protocols. L-Glu-L-Trp treatments also proved useful for alleviating certain symptoms of systemic toxicity in patients with acute bacterial, viral, and parasitic infections.
HIV-infected patients are one group of immunocompromised subjects that may benefit from treatments with Rxe2x80x2-Glu-Trp-Rxe2x80x3, however, it is understood that such treatments are not intended as a cure for AIDS or ARC, but rather for possible use in treating complications of HIV-infection, e.g. opportunistic bacterial and viral infections.
Embodiments of the invention provide methods of treatment using Rxe2x80x2-Glu-Trp-Rxe2x80x3 pharmaceutical preparations to induce a heightened state of cell mediated immunity, humoral immunity, or innate resistance to infection.